fix: copy background image to avoid re-encoding

[robertkill]

The original implementation was re-encoding the JPEG image when saving to both background.jpg and background_in_theme.jpg files, which could cause quality degradation and performance issues. This fix adds a copyFile function to duplicate the file without re-encoding, preserving image quality and improving efficiency.

Log: Fixed background image quality issue in GRUB theme

Influence:

1. Test that background images are properly displayed in GRUB menu
2. Verify both background.jpg and background_in_theme.jpg files are created
3. Check that image quality is maintained without artifacts
4. Test with different image formats and sizes
5. Verify the copy operation works correctly with file permissions

fix: 复制背景图片避免重复编码

原实现在保存到 background.jpg 和 background_in_theme.jpg 文件时都会重新 编码 JPEG 图像，这可能导致质量下降和性能问题。此修复添加了 copyFile 函数
来复制文件而不重新编码，保持图像质量并提高效率。

Log: 修复了 GRUB 主题中的背景图片质量问题

Influence:

1. 测试 GRUB 菜单中背景图片是否正确显示
2. 验证 background.jpg 和 background_in_theme.jpg 文件是否都创建成功
3. 检查图像质量是否保持，没有出现伪影
4. 使用不同格式和大小的图片进行测试
5. 验证复制操作是否正确处理文件权限

PMS: BUG-315809

Summary by Sourcery

Use file copying instead of re-encoding for GRUB background images to preserve quality and improve efficiency.

Bug Fixes:

• Prevent JPEG quality degradation by avoiding redundant re-encoding of background images.

Enhancements:

• Introduce copyFile function to duplicate background.jpg as background_in_theme.jpg without re-encoding.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Refactor setBackground to preserve image quality and improve performance by copying the JPEG file instead of re-encoding it for the second output, with explicit error handling for each step.

Sequence diagram for the updated background image saving process

sequenceDiagram
    participant setBackground
    participant os
    participant logger
    participant copyFile
    setBackground->os: Stat(fallbackDir)
    os-->>setBackground: exists
    setBackground->saveJpeg: saveJpeg(bgImg, background.jpg)
    saveJpeg-->>setBackground: error or success
    alt saveJpeg error
        setBackground->logger: Fatal(err)
    else saveJpeg success
        setBackground->copyFile: copyFile(background.jpg, background_in_theme.jpg)
        copyFile-->>setBackground: error or success
        alt copyFile error
            setBackground->logger: Fatal(err)
        end
    end

Loading

Class diagram for the new copyFile function integration

classDiagram
    class setBackground {
        +setBackground(bgFile string)
    }
    class copyFile {
        +copyFile(src string, dst string) (written int64, err error)
    }
    setBackground --> copyFile: uses
    class logger {
        +Fatal(err error)
    }
    setBackground --> logger: error handling
    class saveJpeg {
        +saveJpeg(img, filename string) error
    }
    setBackground --> saveJpeg: saves JPEG

Loading

File-Level Changes

Change	Details	Files
Use file copying to avoid re-encoding the background image	Save the background image once with saveJpeg Call copyFile to duplicate background.jpg as background_in_theme.jpg Separate error checks and logger.Fatal calls for saveJpeg and copyFile	adjust-grub-theme/main.go

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[deepin-ci-robot]

deepin pr auto review

这段代码的修改看起来是为了优化背景图片的处理方式，但存在一些可以改进的地方：

1. 错误处理改进：

   • 当前代码在两个地方都使用了 logger.Fatal(err)，这会导致程序直接退出。更好的做法是统一错误处理，可以考虑返回错误让调用者决定如何处理。

2. 代码结构优化：

   • backgroundFile 和 backgroundInThemeFile 的定义可以更靠近它们的使用位置，提高代码的可读性。
   • 可以考虑将文件路径的构建提取为一个单独的函数，提高代码的可维护性。

3. 性能考虑：

   • 使用 copyFile 而不是重新编码是正确的做法，这确实能提高性能并避免质量损失。
   • 但应该确保 copyFile 函数本身是高效的，最好使用缓冲区来复制文件。

4. 代码安全：

   • 文件操作前应该检查目标目录是否存在且有写入权限。
   • copyFile 函数应该检查源文件是否存在。

5. 命名规范：

   • 变量名 bgImg 可以更具描述性，比如 backgroundImage。

建议的改进代码：

func setBackground(bgFile string) error {
    // ... 其他代码保持不变 ...

    fallbackDir := getFallbackDir()
    _, err := os.Stat(fallbackDir)
    if err == nil {
        // 构建文件路径
        backgroundFile := filepath.Join(fallbackDir, "background.jpg")
        backgroundInThemeFile := filepath.Join(fallbackDir, "background_in_theme.jpg")
        
        // 保存JPEG图片
        if err := saveJpeg(bgImg, backgroundFile); err != nil {
            return fmt.Errorf("failed to save background image: %v", err)
        }
        
        // 复制文件到主题目录
        if err := copyFileWithBuffer(backgroundFile, backgroundInThemeFile); err != nil {
            return fmt.Errorf("failed to copy background image: %v", err)
        }
    }
    
    return nil
}

// 带缓冲区的文件复制函数
func copyFileWithBuffer(src, dst string) error {
    sourceFile, err := os.Open(src)
    if err != nil {
        return err
    }
    defer sourceFile.Close()

    destFile, err := os.Create(dst)
    if err != nil {
        return err
    }
    defer destFile.Close()

    // 使用4KB的缓冲区
    buf := make([]byte, 4096)
    _, err = io.CopyBuffer(destFile, sourceFile, buf)
    return err
}

这样的改进提高了代码的健壮性、可维护性和性能，同时提供了更好的错误处理机制。

[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: mhduiy, robertkill

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